Richard Stallman (RMS) started GNU in 1983, as a project to create a
complete free operating system. In the text of the GNU
Manifesto, he
mentioned that there is a primitive kernel. In the first GNUsletter,
Feb. 1986, he says that GNU's kernel is TRIX, which was developed at
the Massachusetts Institute of Technology.

By December of 1986, the Free Software Foundation (FSF) had "started
working on the changes needed to TRIX" [Gnusletter, Jan. 1987].
Shortly thereafter, the FSF began "negotiating with Professor Rashid
of Carnegie-Mellon University about working with them on the
development of the Mach kernel" [Gnusletter, June, 1987]. The text
implies that the FSF wanted to use someone else's work, rather than
have to fix TRIX.

In [Gnusletter, Feb. 1988], RMS was talking about taking Mach and
putting the Berkeley Sprite filesystem on top of it, "after the parts
of Berkeley Unix... have been replaced."

Six months later, the FSF is saying that "if we can't get Mach, we'll
use TRIX or Berkeley's Sprite." Here, they present Sprite as a
full-kernel option, rather than just a filesystem.

In January, 1990, they say "we aren't doing any kernel work. It does
not make sense for us to start a kernel project now, when we still
hope to use Mach" [Gnusletter, Jan. 1990]. Nothing significant occurs
until 1991, when a more detailed plan is announced:

We are still interested in a multi-process kernel running on top of
Mach. The CMU lawyers are currently deciding if they can release Mach
with distribution conditions that will enable us to distribute it. If
they decide to do so, then we will probably start work. CMU has
available under the same terms as Mach a single-server partial Unix
emulator named Poe; it is rather slow and provides minimal
functionality. We would probably begin by extending Poe to provide
full functionality. Later we hope to have a modular emulator divided
into multiple processes. [Gnusletter, Jan. 1991].

RMS explains the relationship between the Hurd and
Linux, where he mentions
that the FSF started developing the Hurd in 1990. As of [Gnusletter,
Nov. 1991], the Hurd (running on Mach) is GNU's official kernel.

Announcements

These are all the announcements made over the years. Most of them were
either sent to the gnu.announce news group or Hurd interest
mailing lists.

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License.